There’s nothing that kills the thrill of a trail ride faster than a flashing check engine light. You’re deep in the woods, the engine sputters, and suddenly your powerful machine feels like it’s running on half its cylinders. You’ve just entered limp mode, and your dashboard is flashing a cryptic message: polaris code 173 3.
I’ve been there, and I know that feeling of frustration. It’s a moment that can turn a great day into a long, slow limp back to the truck. But what if I told you that this specific code is often something you can diagnose and fix yourself with just a few common tools?
In this complete guide from FatBoysOffroad, we’re going to pull back the curtain on this common fault code. We’ll break down what it means, show you exactly how to find the problem, and walk you through the steps to get your Polaris running at full power again. Let’s get those wrenches turning and get you back on the trail.
What Exactly is Polaris Code 173 3? Decoding the Message
First things first, let’s translate what your machine is trying to tell you. Diagnostic trouble codes (DTCs) aren’t just random numbers; they’re a specific language. The polaris code 173 3 breaks down like this:
- SPN 173: This is the “Suspect Parameter Number,” and it points directly to the Exhaust Gas Temperature (EGT) Sensor 1. This sensor is a critical component that measures the heat of the exhaust gases leaving your engine.
- FMI 3: This is the “Failure Mode Identifier,” which tells you the type of problem. FMI 3 means “Voltage Above Normal, or Shorted to High Source.”
In simple terms, your machine’s brain, the Engine Control Unit (ECU), is seeing a voltage signal from the EGT sensor that is much higher than it should be. The ECU knows this reading is impossible under normal conditions, so it flags a fault to protect your engine.
Why the EGT Sensor Matters
Think of the EGT sensor as a guardian for your engine. Its primary job is to monitor exhaust temperatures to prevent catastrophic failure, especially on turbocharged models like the RZR or Ranger.
If temperatures get too high, pistons can melt and turbos can be destroyed. The ECU uses the EGT sensor’s data to adjust fuel mixture and boost, keeping everything within a safe operating range. When it gets a bad signal (like an impossibly high voltage), it plays it safe and cuts power—triggering limp mode.
Telltale Symptoms: How Your Polaris Machine Warns You
When the ECU logs code 173 3, it won’t be shy about letting you know something is wrong. The symptoms are designed to get your attention immediately.
The most common signs include:
- The Check Engine Light (CEL): This is your first and most obvious warning. It will illuminate on your dash and stay on.
- Limp Mode Activation: To prevent damage from a potential (or perceived) overheating event, the ECU will drastically reduce engine power. You’ll notice a significant lack of acceleration and a much lower top speed.
- Poor or Erratic Performance: Even before full limp mode, you might notice the engine running rough, hesitating, or just feeling “off.”
Recognizing these symptoms is the first step. The next is diving in to find the root cause, which is often simpler than you might think.
The Usual Suspects: Common Problems Causing Code 173 3
While the code points to the EGT sensor circuit, the problem isn’t always the sensor itself. Based on our experience in the shop and on the trail, the issue almost always falls into one of three categories. This is a crucial part of our polaris code 173 3 guide.
H3: The Most Likely Culprit: Damaged Wiring or Connectors
Your Polaris is built to take a beating, but its wiring harness is often the first casualty. Wires get splashed with mud, blasted with water, snagged by branches, and constantly vibrated.
A “short to high source” often means a signal wire has rubbed through its insulation and is touching a power wire in the same harness. It can also mean the connector itself is compromised. Look for green, crusty corrosion inside the plug or pins that have backed out and aren’t making a solid connection.
H3: The Second Suspect: A Failed EGT Sensor
The EGT sensor lives in a brutal environment—the exhaust manifold. It endures thousands of extreme heat cycles, vibrations, and corrosive gases. Over time, the internal components can simply fail.
When an EGT sensor fails internally, it can create an open circuit, which the ECU often interprets as an extremely high voltage reading, thus triggering the FMI 3 code. This is one of the most common problems with polaris code 173 3.
H3: The Rare Case: A Faulty Engine Control Unit (ECU)
Before you even think about the ECU, exhaust every other possibility. ECU failure is extremely rare. In almost all cases, the problem will be found in the wiring or the sensor itself. Always treat the ECU as the absolute last resort after thorough testing.
Your Step-by-Step Polaris Code 173 3 Guide to Diagnosis
Alright, let’s get our hands dirty. This section is all about how to polaris code 173 3 diagnosis effectively. Follow these steps methodically, and you’ll pinpoint the problem. Safety first: make sure the engine is completely cool before working near the exhaust system.
H3: Essential Tools for the Job
You don’t need a full professional shop, but having the right tools makes the job much easier. Gather these before you start:
- Safety Glasses
- Mechanic’s Gloves
- A good flashlight or headlamp
- Socket set and wrenches (for removing the sensor if needed)
- A good quality Multimeter (this is non-negotiable for electrical diagnosis)
- Contact cleaner and a small brush (like a toothbrush)
- Dielectric grease
H3: Step 1: Visual Inspection – The 10-Minute Check
Start with your eyes. Locate the EGT sensor—it’s a small probe screwed into the exhaust manifold or pipe, with a wire coming out of it. Carefully trace that wire from the sensor back towards the main engine harness.
Look for anything that seems out of place:
- Is the wire melted or touching the hot exhaust?
- Are there any cuts, scrapes, or sections where the wire looks pinched?
- Is the wire securely clipped in place, or is it dangling where it could get caught?
Many issues are found right here. A simple zip tie to secure a loose wire can be a permanent fix.
H3: Step 2: Inspect and Clean the Connector
Find where the EGT sensor’s harness plugs into the main engine harness. Carefully disconnect it. You may need to press a small tab to release the lock.
Shine your light inside both ends of the connector. Do you see any white or green corrosion? Are any of the metal pins bent, pushed back, or broken? Moisture is the enemy of electrical connections. If you find corrosion, spray it liberally with contact cleaner and gently scrub it with your brush. Let it dry completely before reconnecting.
H3: Step 3: Test the EGT Sensor with a Multimeter
This is the definitive test to see if the sensor itself has failed. Set your multimeter to the “Ohms” (Ω) setting, often at 2K or 20K.
- With the sensor unplugged, touch the two multimeter probes to the two pins on the sensor side of the connector.
- At room temperature (around 70°F / 21°C), a good Polaris EGT sensor should read approximately 200-220 Ohms.
- If you get a reading of “OL” (Open Loop), “1”, or something infinitely high, the sensor is internally broken and must be replaced. A reading of zero means it’s shorted out.
This simple test provides clear, actionable results and is one of the most important polaris code 173 3 tips we can offer.
The Fix: Replacing the Sensor and Best Practices
If your diagnosis points to a bad sensor, the next step is replacement. Following a few polaris code 173 3 best practices here will ensure a lasting repair.
H3: Sourcing the Right Part
We always recommend using an OEM (Original Equipment Manufacturer) part from Polaris for critical sensors. While aftermarket options exist, the quality can be inconsistent. Your EGT sensor is vital for engine protection, so this isn’t the place to cut corners.
H3: The Replacement Process
Replacing the sensor is straightforward. It’s essentially like removing a spark plug.
- Make sure the exhaust is completely cool.
- Use the correct size wrench or deep socket to break the old sensor loose. It may be tight, so use steady pressure.
- Before installing the new sensor, apply a small amount of high-temp anti-seize compound to the threads. This will make future removal much easier. Be careful not to get any on the sensor tip itself.
- Thread the new sensor in by hand to avoid cross-threading, then tighten it to the manufacturer’s specified torque (or just snug it up firmly).
- Route the new wire along the original path, securing it away from heat and moving parts.
- Apply a small dab of dielectric grease to the connector pins before plugging it in. This seals out moisture and prevents future corrosion.
H3: Clearing the Code and The Test Ride
After the repair, you need to clear the code. You can do this by disconnecting the machine’s battery for about 15 minutes. Once reconnected, start the engine. The check engine light should be off.
The final step is a thorough test ride. Ride the machine as you normally would to ensure the code doesn’t return and that full power has been restored.
Benefits of a Proper Fix: Engine Health and Peace of Mind
Fixing this code correctly offers more than just turning off a light. The benefits of polaris code 173 3 resolution are significant. You are restoring your engine’s primary safety system, ensuring it can protect itself from damage.
A properly functioning EGT system also allows the ECU to manage fuel delivery more effectively. This leads to better performance, improved fuel economy, and cleaner emissions—making your fix an eco-friendly polaris code 173 3 solution. A proper repair is a sustainable polaris code 173 3 approach that prevents bigger, more costly problems down the road.
Frequently Asked Questions About Polaris Code 173 3
Can I still ride my Polaris with code 173 3?
You can, but you shouldn’t. The machine will be in limp mode, which means you’ll have severely limited power. More importantly, you’re riding without a key safety sensor, putting your engine at risk if a real overheating problem were to occur.
How much does it cost to fix polaris code 173 3?
If it’s a wiring issue you can fix yourself, the cost could be next to nothing. If the EGT sensor needs replacement, the part itself typically costs between $80 and $150, depending on your model. Doing the labor yourself saves you a significant amount over a dealer repair.
Can I just bypass or delete the EGT sensor?
We at FatBoysOffroad strongly advise against this. Deleting the sensor requires an ECU tune and removes a critical engine protection feature. It’s a risky move that could lead to a catastrophic engine failure that would cost thousands to repair.
Tackling a check engine light can feel intimidating, but with a logical approach, you can solve many issues like polaris code 173 3 right in your own garage. By following this guide, you’ve not only saved money but also gained a deeper understanding of how your machine works.
So take your time, be methodical, and trust the process. You’ll have that code cleared and be back to tearing up the trails with full power in no time. Ride safe, and we’ll see you out there!
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